1. Field of the Invention
This present invention relates generally to an improved vertical auger utilized in pneumatic spreader systems for distribution of granular agricultural crop and soil treating chemicals, and more particularly to an improved system for achieving uniform distribution of such products through the use of an improved self regulating vertical auger which effectively reduces the inherent delay in product metering.
2. Description of the Prior Art
The present invention finds particular utility for use in combination with those certain agricultural spreader systems such as disclosed in U.S. Pat. No. 5,092,526, issued Mar. 3, 1992, to Takata, and entitled Venturi System For Agricultural Spreaders Of Solid Particles; U.S. Pat. No. 5,018,668, issued May 28, 1991, to Bauer, and entitled Method And Apparatus For Initiating Rotation Of Vertical Auger Devices; and U.S. Pat. No. 4,964,575, issued Oct. 23, 1990, to Takata, and entitled Boom Flow Control Mechanism For Pneumatic Spreaders, the aforementioned patents being assigned to the same assignee as the present invention, and hereby incorporated by reference in their entirety. The apparatus of the present invention allows an agricultural spreader system conveyor and vertical auger to shut down when no product is being metered from the metering device without exhibiting any substantial `puff` of product when the system is restarted, and while simultaneously enhancing the accuracy of the air spread in the particular spreader system.
Pressurized pneumatic systems utilizing a single distribution head delivering or metering a supply of granular or particulate material for controlled discharge of such material from a plurality of elongated booms have been employed in the past. However, the systems currently in use normally deliver granular products through use of a vertical auger which is designed to rotate under conditions of substantially constant speed and constant torque. Occasionally, and particularly when the system has been shut down for an interval of time with material remaining in the vertical auger, some uneven flow may occur at the time of vertical auger start-up. The non-uniformity may result from the packing of particulate material within the auger during the interval of shutdown, and upon start-up, the rotation of the vertical auger may occur in a non-uniform fashion. The present invention provides a reliable system for maintaining the distribution and application rate at a substantially uniform and constant level through the active booms.
Agricultural techniques require the utilization of soil treating agents and crop treating agents to either encourage, discourage, destroy or inhibit plant growth. Such agents may generally be characterized as crop treating chemicals, and include materials designated as nutrients such as fertilizers, and pesticides such as insecticides and herbicides including pre-emergent and/or post-emergent growth inhibitors. Accordingly, the term "crop treating chemical" is used in a comprehensive sense to incorporate those various ingredients utilized in agriculture to treat either the soil, the growing crop or plants, or certain insects which may damage the crop. Active materials used for treatment are commonly found in one of three forms, including water soluble, water wettable, particulate solid or in surface-impregnated solid form. In connection with the present invention, granular materials and/or surface-impregnated (wetted) granular materials are of particular interest, with the system of the present invention being particularly adapted for use in connection with the selective and uniform distribution of such materials through the system and onto the soil or other surfaces being treated.
In the treatment of agricultural fields and crops through spreading of one or more active treating ingredients, the efficiency of the treatment operation may be enhanced if the distribution of the ingredients is maintained at a uniform and/or controllable rate, particularly at the point of ingredient metering. Uniform application rates continue to be an important factor, particularly with the use of certain pesticides and/or herbicides which require a predetermined application rate in order to be effective, and not otherwise harmful to the crop being treated. Occurrences of under-application or over-application of crop treating materials may result in application being either ineffective or, in certain instances, harmful to the crop. Additionally, the efficiency of the operation may be enhanced if the actual load required to be carried by the spreading equipment is reduced. Therefore, the utilization of dry particulate solids will substantially reduce the load requirement, inasmuch as water or other treatment medium or treatment vehicle is not required. The need for multiple passes may be reduced if surface-impregnated granular material may be uniformly spread, such as through the use of a granular fertilizer having a surface impregnated with a particular pesticide. The utilization of pressurized pneumatic systems will normally eliminate or substantially reduce the vehicle load by eliminating the need for large quantities of water, since pneumatic systems normally utilize a compressor to generate a supply of compressed air in lieu of a liquid plus liquid pressure source as a means to create a medium for accomplishing delivery of the treating ingredient onto the soil.
Pneumatic spreader systems typically are mounted upon self-propelled vehicles, thereby providing a means for achieving the distribution. In order to render these systems efficient, elongated booms are employed, and it is not uncommon for such booms to extend outwardly a distance of 20 feet or more from the center axis of the vehicle. When the operator reaches the end of a field, the entire capability of the system is shut down for turn-around to avoid any excessive or double-coverage. In order to render the system more highly advantageous, this interruption of flow is achieved while maintaining substantially uniform application rates upon start-up. An added advantage of the system permits intermittent shut-down of certain booms when the fertility index varies across the field being treated, with uniform distribution being achieved upon the occurrence of start-up.
During normal operation, the vertical auger becomes loaded with granular material. In those instances when the machine reaches the end of the field, and is being turned around for initiation of the next application run, the material remaining in the augers presently in use tends to flow downwardly along the ramp formed by the auger flutes, thereby becoming more densely packed within the confines of the auger. Occasionally, on these occurrences, the auger resists initial start-up until the packed material breaks away, and auger rotation is commenced. Initiation of auger rotation accordingly requires higher-than normal torque, and preferably lower-than normal running rates until complete breakaway occurs for augers presently in use in pneumatic spreader systems. In most instances, the interval of time required for break-away is equivalent to somewhere between 180 degrees of auger rotation, or somewhat greater period.
As indicated hereinbefore, uniformity of distribution of particulate materials depends to a certain extent upon operation of the entire system, including the distribution head and the material transferring conduits, as well as the vertical auger. In order to preserve operational integrity and predictability, therefore, uniformity of rate of rotation of the vertical auger is a desirable feature.
Furthermore, from the moment product is metered from the control point (e.g. the meter wheels) until it arrives on the ground or other area of interest, the total delay is approximately 2 seconds for pneumatic air spreader systems presently in use. At 20 mph this correlates to approximately 60 feet traversed, and a spread area of 3600 ft.sup.2 or approximately 8.3% of an acre. In the case of highly dynamic vehicular steering, the system has no other means of improving accuracy than to speed up the reaction time, or reduce system delay.
Pneumatic air spreader systems presently in use allow the conveyor and vertical auger to shut down when no product is being metered from the metering wheels. This allows some product to travel back down the flighting of the vertical auger in static mode, resulting in what has been described as a `puff` of product when the system is restarted. Some systems presently in use have given consideration to keeping the vertical auger running during turns or have delivered higher torque rates to the vertical auger when the system is restarted. Such attempts to achieve accurate spreading have created the largest system delays during product application or else have continued to generate some `puff` of product when the system is restarted.
The present invention addresses the aforementioned problems in a manner to both increase the accuracy (reduce the `puff`) and decrease the system delay. The features of the present invention have been found desirable for improving the performance of systems when the operation of the vertical auger has been temporarily interrupted.
This increased accuracy and decreased system delay are achieved through the utilization of a self-regulating vertical auger which traps the product to be delivered, more or less in position in the auger stream when the vertical auger is stopped.